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Cyanoacrylate
Cyanoacrylate is the generic name for substances such as methyl-2-cyanoacrylate, which is typically sold under trademarks like Superglue and Krazy Glue, and 2-octyl cyanoacrylate, which is used in medical glues such as Dermabond and Traumaseal. Cyanoacrylate adhesives are sometimes known as "instant adhesives". The acronym "CA" is quite commonly used for industrial grades. In radio control, cyanoacrylates are used for repair and assembly of both foam and built-up model aircraft. They are also used for securing tires to wheels on R/C cars and trucks (see below) and may be used for general repair of any type of model. Special, odorless CA must be used on foam aircraft as regular Krazy Glue-types will attack and dissolve the foam. History Cyanoacrylate was discovered during World War II when searching for a way to make synthetic gun-sights (a substitute for spider silk). It did not solve this problem, since it stuck to all the apparatus used to handle it. Later it was developed into a more useful form by the Eastman Kodak company in 1958. The term is now used to refer to a range of adhesives based on similar chemistry. Medicine The use of cyanoacrylate glues in medicine was considered fairly early on. Eastman Kodak and Ethicon began studying whether the glues could be used to hold human tissue together for surgery. In 1964 Eastman submitted an application to use cyanoacrylate glues to seal wounds to the United States Food and Drug Administration (FDA). Soon afterward, the glue did find use in Vietnam--reportedly in 1966 cyanoacrylates were tested on-site by a specially trained surgical team, with impressive results. Properties In its liquid form, cyanoacrylate consists of monomers of cyanoacrylate molecules. Methyl-2-cyanoacrylate (CH2=C(CN)COOCH3 or C5H5NO2) has a molecular weight equal to 111.1, a flashpoint of 79 ºC, and a density of 1.1 times the density of common water (H2O). Ethyl-2-cyanoacrylate (C6H7NO2) has a molecular weight equal to 125 and a flashpoint of 75 °C. Generally, cyanoacrylate is an acrylic resin which rapidly polymerize in the presence of water (specifically hydroxide ions), forming long, strong chains, joining the bonded surfaces together. Because the presence of moisture causes the glue to set up, exposure to moisture in the air can cause a tube or bottle of glue to become unusable over time. To prevent an opened container of glue from setting before use, it must be stored in an airtight jar or bottle with a package of silica gel. Another important trait is that cyanoacrylate sets up fast, often in less than a minute. A normal bond reaches full strength in two hours, and is waterproof. There are also accelerants that can force a set-up as fast as two or three seconds, at some loss of strength. These acccelerants, commonly referred to as "kickers," make the use of cyanoacrylates possible in assembling R/C model aircraft. Acetone, which is found in nail polish remover, is a commonly available solvent capable of softening cured super glue. Cold temperatures cause cyanoacrylate to become brittle. Cyanoacrylate's bond can be weakened, allowing disassembly, by placing a glued object in a household freezer for several hours. Uses Cyanoacrylate is a tenacious adhesive, particularly when used to bond non-porous materials or those that contain minute traces of water. As such it is very good at bonding body tissue, and while this effect can be a nuisance (or even dangerous) for everyday use, it has been exploited for the benefit of sutureless surgery. This technique was shown in the werewolf film Dog Soldiers, where Sean Pertwee's character get his guts repaired with a large tube of Superglue. Cyanoacrylates are often used to assemble prototype electronics and as retention dressings for nuts and bolts. Their effectiveness in bonding metal and general versatility have also made them popular amongst scale model, miniatures and R/C hobbyists. One non-adhesive use for cyanoacrylate is as a forensic tool. Fumes from warmed CA can develop latent fingerprints on surfaces. The invisible fingerprint residues react with the CA fumes and atmospheric moisture to become visible and can then be recorded. This technique was shown in the film Beverly Hills Cop II. In RC, the most common use for Cyanoacrylate on land vehicles is bonding the tires to the rims. Because RC vehicle tires are not pneumatically inflated, there is no pressure to hold the tire to the rim. In addition, RC tires don't have a tire bead in the sense that 1:1 vehicles do. Instead of a strong, inflexible bead, there is just a flat strip of flexible rubber that provides a bonding surface for the glue. If the tires weren't glued to the rims, they would slip under acceleration and be prone to being pulled off the rim, especially while turning. Category:Chemicals Category:Materials